This paper focuses on the determinants of military spending in Africa by considering the role played by institutions. With data obtained between the years 1996–2019, the Driscoll and Kraay fixed effects, the Generalised Method of Moments (GMM), and the Bayesian Model Averaging (BMA) estimators are used. The findings suggest that government size, trade freedom, economic risk, and political risk decrease military spending, whereas government stability and military involvement in politics are found to raise it. Using alternative institutional variables, we find that corruption, government effectiveness, political stability, regulatory quality, the rule of law, and voice and accountability significantly diminish military spending in Africa. In addition, concerning the economic determinants, the results reveal that trade openness and total natural resource rents reduce military spending, while GDP per capita, inflation, and foreign debt stocks increase it. Looking at strategic determinants, arms imports, urban population, and ethnic tensions positively affect African military expenditures. Robustness checks show that these results change once regional specificities are considered. The study concludes that institutional factors could be an engine for evolution in Africa’s military spending.